Ignition system and magneto therefor



Y 6 J. B-STEPHENS' I 3,461,851 I I IGNITION SYs'rEni AND MAGNMO THEREFQR- Original Fileddan. is. 1966 mvzn'roa'. JOE BARON STEPHENS United States Patent 3,461,851 IGNITION SYSTEM AND MAGNETO THEREFOR Joe Baron Stephens, Columbus, Miss, assignor to AMBAC Industries, Incorporated, Columbus, Miss., a corporation of New York Continuation of application Ser. No. 520,380, Jan. 13, 1966. This application Oct. 7, 1968, Ser. No. 781,664 lint. Cl. F02p 1/08; H02k 11/00 US. Cl. 123-149 12 Claims SCT OF THE DISCLOSURE An ignition system for an engine provides an inductive means for generating suflicient potential to produce a spark at at least one spark gap ignition device. The ignition system includes a magneto having at least one winding, a charge storage means (e.g., capacitor) to which the output of the at least one winding is connected and a switch means for selectively connecting the charge storage means to the inductive means. The switch means has a control terminal which is responsive to a suitable signal to connect the charge storage means to the inductive means. The at least one winding of the magneto is connected to the charge storage means by unidirectional current flow means, which assures charging by current of one polarity. The control terminal of the switch means is connected to the at least one magneto winding so that current of the same polarity flowing in the opposite direction from that reaching the charge storage means will reach the control terminal and cause the switch means to connect the charge storage means to the inductive means. Preferably two windings are provided on the magneto, one winding being of low impedance and the other of high impedance, connected to impart their cumulative effect to the storage means. The magneto includes a stator having at least a magnetic core with the at least one winding thereon and a rotor mounted for rotation relative to the stator. The rotor has permanently magnetized teeth alternating north and south poles around the circumference of the rotor, which teeth pass successively in close proximity to the magnetic core of the stator.

This application is a streamlined continuation of Ser. No. 520,380, filed Jan. 13, 1966, now abandoned.

The present invention relates to an ignition system driver and more specifically a magneto device and circuit elements for use with the ignition system of an engine employing no battery or other stand-by source of power.

There has been a great and continuing need for a compact ignition system driver for use in particular with light portable engine devices, such as out-board engines for boats. Such a system is preferably designed to do completely without use of a battery in order to further the aim of lightness and compactness and to avoid the need for carrying along a separate battery system. The present invention relates to such an ignition system driver which employs a relatively simple, thin, flat, lightweight magneto and just a few simple and conventional circuit elements in its preferred embodiments. The magneto itself is engine driven and, therefore, rotates as the engine rotates at a speed proportional to engine speed. In devices, such as outboard engines which commonly require initial manual cranking, this device is operative even at the relatively slow speeds of manual cranking and equally well at high speeds including the highest speeds of operation.

More specifically, the ignition system driver of the present invention comprises a magneto having a magnetic field which produces changes in the magnetic flux in at least one winding. Means is provided to store charge and means for connecting the charge storage means to the magneto winding, including unidirectional current flow means, is provided so that the charge storage means will be charged by current'of one polarity flowing in one direction in the magneto winding due to the relative movement between the magnetic field and the conductor of the winding. Ignition systems contemplated by this invention ordinarily include inductive means coupled to the spark gap ignition device for generating suflicient potential to produce a spark in such device. Switch means is provided for selectively connecting the charge-storage means to the inductive means and having a control terminal responsive to a suitable signal applied to the control terminal to connect the charge-storage means to the inductive means. The control terminal of the switch means is coupled to the magneto winding by means which permits current flow only in the opposite direction from that reaching and charging the charge-storage means thereby to cause the switch means to connect the chargestorage means to the inductive means and produce ignition. The means which permits current flow in only one direction may be omitted in certain cases where the control terminal of the switch is potential sensitive.

In preferred embodiments, the charge-storage means is a capacitor, the switching means is a silicon-controlled rectifier and the unidirectional means are simple diodes arranged appropriately. The control terminal connection of the silicon-controlled rectifier also preferably employs diodes to assure that only current of the same polarity flowing in the opposite direction from that reaching the charge storage means will reach the control terminal and cause the switch means to connect the charge storage means to the inductive means. The magneto may take a number of forms, preferably consisting of a rotor having alternate teeth around the circumference of the rotor polarized north and south and a stator having magnetic circuits for each winding. Preferably there are two windings wound in such direction that they may be coupled together to supply a cumulative signal to the chargestorage means. One of the windings has high impedance and the other has low impedance so that at its slow speed the high impedance device produces a relatively large output and at high speed the low impedance device produces a relatively large output. The arrangement is preferably such that both windings may cumulatively add to the total current flow to the capacitor but the low impedance winding also may supply current directly to the charge-storage means without the need to pass through the high impedance winding.

For a better understanding of the present invention, reference may be had to the following drawings, in which:

FIG. 1 is a schematic drawing of the preferred form of the ignition system driver showing a plan view of the magneto in highly diagrammatic form;

FIG. 2 is a side elevational view of the magneto shown in FIG. 1; and

FIG. 3 is a partial view corresponding to FIG. 1 showing modification of the circuit for use with a one coil magneto.

Referring first to FIG. 1, the' drawing shows a magneto generally designated 10 and consisting in the illustrated embodiment of a rotor 11 and a stator 12, which stator carries a low impedance winding 13 and a high impedance winding 14. While a single winding may be used in accordance with the present invention, two windings as shown offer the possibility of more uniform outputs at high and low speeds. The windings 13 and 14 are wound on the stator and arranged in magnetic circuits such that they may be connected together as shown to produce a cumulative output across both the windings. At slow speed a high positive output from winding 14 passes through diode 16 to charge the charge-storage means, a capacitor 18, since the switching means 20 is open and will not pass the current. The circuit in this case is from ground through diode 22, through winding 13, winding 14, through diode 16 to capacitor 18, whose other side is also grounded. At high rotor speeds, the output of winding 14 becomes minimum but the output of winding 13 increases and flow in this case proceeds through diode 24 to capacitor 18. The circuit in this case is from ground through diode 22, through winding 13, through diode 24 to capacitor 18 whose other side is connected to ground. To repeat, the switch 20 is open at this particular time.

As the magneto moves to its next pole position, the polarity of the current in the windings reverses and the negative output is blocked from reversing the charge on capacitor 18 by diodes 16 and 24. The positive output flowing in the opposite direction, however, flows through diode 28 and current limiting resistor 30 to a control terminal of the switching circuit 20 to close the switch. The switching circuit 20 is preferably a silicon controlled rectifier. The potential thus applied to the control terminal of the silicon controlled rectifier turns on the rectifier, which then acts like a closed switch, to allow the charge accumulated on capacitor 18 to flow through the primary 34 of the spark coil 36, thereby inducing a very high voltage in secondary 38 in a conventional manner. Diode 28 may be omitted in many cases where an electronic switch like a silicon controlled rectifier is employed since a potential of a given size and certain polarity is required to fire the silicon controlled rectifier in any event. This causes an ignition device spark gap in the circuit of the secondary to break down and fire. To initiate the switching, current may flow from the diode 40 side of winding 13 through diode 28, and current-limiting resistor 30 to the control terminal of the silicon controlled rectifier 20. High frequency transients are by-passed through capacitor 42 to prevent damage to the silicon controlled rectifier. Current from capacitor 18 must flow through the silicon com trolled rectifier switch 20 since diodes 16 and 24 block flow back toward the magneto. The system will normally work in the manner described unless the kill switch 44 closes the normally charged side of capacitor 18 to ground so that both sides of the capacitor are grounded and no charging is possible.

In the system shown, there are six spark gaps or spark plugs 50, one side of each of which is connected to ground. The other side is connected sequentially to the rotor 52 of the distributor 54 whose shaft is connected to the means driving the magneto shaft so that the two rotate in synchronism. The rotor 52 is electrically connected to the secondary 38 of the spark coil 36 and, if the timing is correctly adjusted so that the capacitor discharges to the spark coil at the time the rotor 52 passes the contact of the distributor of a spark plug, proper discharge should take place. This involves proper relationship in the rotation between the distributor rotor and the magneto rotor 11 which must be arranged so that upon triggering of the switching circuit 20 the distributor rotor is in place to connect the spark plug to the spark coil.

The system illustrated is a high tension system. The invention applies as well to a low tension system wherein there are separate transformers for each spark plug between the distributor and the respective spark plugs.

The magneto rotor itself is preferably composed of a pair of magnetic members 60 and 62 separated by a face polarized magnet 64, that is a disc, typically of a suitable ferrite material, one flat face of which is polarized south and the other of which is polarized north as shown. The two pole pieces 60 and 62 are each preferably provided with as many teeth as there are ignition devices or spark plugs and these are advantageously arranged with pole teeth interspersed so that there will be alternate north and south poles confronting stator pole positions at uniform intervals. The pole piece 60 assumes north poles where pole piece 62 assumes south poles because of the conductive effect of the magnet 64. The stator 12 may alternatively consist of two stator elements, each providing a complete magnetic circuit of the windings 13 and 14. In the arrangement shown, the respective windings are wound on stator pole pieces 66 and 68 which are shown confronting north poles at the moment represented by the position of the rotor in the drawing. A U-shaped magnetic path in the case of winding 13 terminates in stator pole piece 70 which confronts a south pole on the rotor in the position shown. Similarly, the magnetic circuit for winding 14 terminates in a stator pole piece 72 which confronts a south pole. Making the stator all one piece is a matter of convenience since the stampings can be made together and stacked conveniently and the windings thereafter wound in place. In the arrangement shown in the drawing, the direction of the magnetic flux through the magnetic core will determine the direction of the windings on the legs shown such that by connection together in the manner shown, the outputs will be cumulative. A common connection between the windings permits positive flow through diode 24 or negative flow through diode 40. The output of winding 14 is passed by diode 16 if positive or rejected by the same diode if negative. The other lead from winding 13 produces positive flow through diode 28 or receives negative flow through diode 22.

With but a single magneto winding, modifications as illustrated in FIG. 3 are required. A moderate impedance winding 14 is substituted, for example, for the high impedance winding 14. The circuit through winding 13 to diode 24 and diode 24 are omitted as are the circuit through diode 50 and diode 40. Diode 28 has been omitted leaving the control terminal of switch 20 to hold off negative potential effects on its own as explained above. Winding 14' is connected to the control terminal of switch 20 through resistor 30 and diode 22 is connected to ground as shown. The connection of winding 14 through diode 16 is the same as the connection of winding 14 in FIG. 1 but a diode 74 is connected to ground between winding 14' and diode 16 in view of omission of diodes 24 and 40.

It will be observed that the magneto construction shown and described can be made relatively very thin. It will also be observed that the rest of the circuit can be made extremely simple. To adapt it to a conventional spark transformer and ignition system needs only a few simple inexpensive diodes, one or two capacitors and a switching circuit which preferably is a silicon-controlled rectifier. The present invention, therefore, offers a very simple and inexpensive system to solve a problem which has represented difiiculties of major proportions in the prior art.

While the system shown is preferred, modifications will occur to those skilled in the art. All such modifications within the reasonable scope of the claims are intended to be within their scope and spirit.

I claim:

1. An ignition system for an engine employing at least one spark gap ignition device and an inductive means coupled to the spark gap ignition device for generating sufiicient potential to produce a spark at such device, comprising:

a magneto having a magnetic field which produces changes in magnetic flux in at least one winding,

a charge storage means,

unidirectional current flow means connecting one end of the charge storage means to one end of said at least one magneto winding so that the charge storage means will be charged by current flowing in one direction in said at least one magneto winding as the magnetic field changes,

first circuit means completing the charging circuit to the charge storage means,

switch means for selectively connecting the charge storage means to the inductive means and having a control terminal so that responsive to a suitable signal applied to the control terminal the switch means connects the charge storage means to the inductive means, and

second circuit means connecting the control terminal of the switch means to the other end of said at least one magneto winding so that current flowing in some part of the said at least one magneto winding in said opposite direction from that charging the charge storage means will reach the control terminal to cause the switch means to connect the charge storage means to the inductive means.

2. An ignition system for an engine employing at least one spark gap ignition device and an inductive means coupled to the spark gap ignition device for generating sufficient potential to produce a spark at such device, comprising:

a magneto having a magnetic field which produces changes in the magnetic flux in at least one winding,

a charge storage means,

unidirectional current flow means connecting one end of the charge storage means to one end of said at least one magneto winding so that the charge storage means will be charged by current flowing in one direction in said at least one magneto winding as the magnetic field changes,

unidirectional current flow means connecting the other side of the charge storage means to complete the charging circuit to the charge storage means and prevent current flow in the reversing direction in said charging circuit,

switch means for selectively connecting the charge storage means to the inductive means and having a control terminal so that responsive to a suitable signal applied to the control terminal the switch means connects the charge storage means to the inductive means, and

circuit means connecting the control terminal of the switch means to the other end of said at least one magneto Winding so that current flowing in some part of the said at least one magneto winding in said opposite direction from that charging the charge storage means will reach the control terminal to cause the switch means to connect the charge storage means to the inductive means.

3. An ignition system for an engine employing at least one spark gap ignition device and an inductive means coupled to the spark gap ignition device for generating suflicient potential to produce a spark at such device, comprising:

a magneto having a magnetic field which produces changes in the magnetic flux in at least one winding,

a charge storage means,

unidirectional current flow means connecting one end of the charge storage means to one end of said at least one magneto winding so that the charge storage means will be charged by current flowing in one direction in said at least one magneto winding as the magnetic field changes,

unidirectional current flow means connecting the other side of the charge storage means to the other end of said at least one winding to complete the charging circuit to the charge storage means and prevent current flow in the reversing direction in said charging circuit,

switch means for selectively connecting the charge storage means to the inductive means and having a control terminal so that responsive to a suitable signal applied to the control terminal the switch means connects the charge storage means to the inductive means, and

circuit means connecting the control terminal of the switch means to the other end of said at least one magneto winding in a circuit which includes a connection to the said one end of the winding so that current flowing in the at least one magneto winding in said opposite direction from that charging the charge storage means will reach the control terminal to cause the switch means to connect the charge storage means to the inductive means.

4. An ignition system for an engine employing at least one spark gap ignition device and an inductive means coupled to the spark gap ignition device for generating sufficient potential to produce a spark at such device, comprising:

a magneto having at least two windings, a first of low impedance and a second of high impedance, at least one of said magneto windings being connected in both charging and firing circuits,

-a charge storage means,

unidirectional current flow means connecting one end of the charge storage means to one end of said at least one magneto winding so that the charge storage means will be charged by current flowing in one di rection in said at least one magneto winding as the magnetic field changes,

unidirectional current flow means connecting the other side of the charge storage means to the other end of said at least one winding to complete the charging circuit to the charge storage means and prevent current flow in the reversing direction in said charging circuit,

switch means for selectively connecting the charge storage means to the inductive means and having a control terminal so that responsive to a suitable signal applied to the control terminal the switch means connects the charge storage means to the inductive means, and

circuit means connecting the control terminal of the switch means to the other end of said at least one. magneto winding in a circuit which includes a connection to the said one end of the winding so that current flowing in the at least one magneto winding in said opposite direction from that charging the charge storage means will reach the control terminal to cause the switch means to connect the charge storage means to the inductive means.

5. The ignition system of claim 4 in which the low impedance and high impedance windings each have their own direct unidirectional current flow means connecting them to the charge storage means.

6. The ignition system of claim 1 in which the switch means includes at least one solid state device.

7. The ignition system of claim 6 in which the switch means is a silicon controlled rectifier.

8. An ignition system for an engine employing at least one spark gap ignition device and an inductive means coupled to the spark gap ignition device for generating suflicient potential to produce a spark at such device, comprising:

a magneto having a magnetic field which produces changes in the magnetic flux in at least one winding and which includes a rotor with permanently magnetized teeth alternating north and south poles around the circumference of the rotor,

a charge storage means,

unidirectional current flow means connecting the charge storage means to the magneto winding so that the charge storage means will be charged by current flowing in one direction in the magneto winding as the magnetic field changes,

switch means for selectively connecting the charge storage means to the inductive means and having a control terminal so that responsive to a suitable signal applied to the control terminal the switch means connects the charge storage means to the inductive means, and

means connecting the control terminal of the switch means to the magneto winding so that current flowing in the opposite direction from that reaching the charge storage means upon reaching the control terminal will cause the switch means to connect the charge storage means to the inductive means.

9. The ignition system of claim 8 in which the magneto rotor is composed of a pair of similar magnetic members each having half of the total pole pieces, one of which supplies north poles and the other of which supplies south poles and the members are positioned relative to one another so that opposite poles are alternated.

10. The magneto system of claim 8 in which the magnetic members are separated by a face polarized magnetic disc.

11. The ignition system of claim 8 in which there are as many poles of each type as there are spark gap ignition devices.

12. The ignition system of claim 8 in which a separate magnetic circuit yoke stator of magnetic material is provided for each winding each with two pole pieces posi- References Cited UNITED STATES PATENTS 3,186,397 6/1965 London 123148 3,198,973 8/1965 Short et a1. 310-153 3,219,877 11/1965 Konopa 123-148 3,253,185 5/1966 Morrison 123148 3,324,841 6/1967 Kebbon et al. 123-149 3,326,199 6/ 1967 McMillen 123-149 LAURENCE M. GOODRIDGE, Primary Examiner US. Cl. X.R. 

